lib/libthread_xu/thread/thr_cond.c

   1 /*
   2  * Copyright (c) 2005 David Xu <davidxu@freebsd.org>
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice unmodified, this list of conditions, and the following
  10  *    disclaimer.
  11  * 2. Redistributions in binary form must reproduce the above copyright
  12  *    notice, this list of conditions and the following disclaimer in the
  13  *    documentation and/or other materials provided with the distribution.
  14  *
  15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  16  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  17  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  18  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  19  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  20  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  21  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  22  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  23  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  24  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  25  *
  26  * $DragonFly: src/lib/libthread_xu/thread/thr_cond.c,v 1.1 2005/02/01 12:38:27 davidxu Exp $
  27  */
  28
  29 #include <stdlib.h>
  30 #include <errno.h>
  31 #include <string.h>
  32 #include <pthread.h>
  33 #include <limits.h>
  34
  35 #include "thr_private.h"
  36
  37 /*
  38  * Prototypes
  39  */
  40 static int cond_init(pthread_cond_t *cond, const pthread_condattr_t *attr);
  41 static int cond_wait_common(pthread_cond_t *cond, pthread_mutex_t *mutex,
  42                     const struct timespec *abstime, int cancel);
  43 static int cond_signal_common(pthread_cond_t *cond, int broadcast);
  44
  45 /*
  46  * Double underscore versions are cancellation points.  Single underscore
  47  * versions are not and are provided for libc internal usage (which
  48  * shouldn't introduce cancellation points).
  49  */
  50 __weak_reference(__pthread_cond_wait, pthread_cond_wait);
  51 __weak_reference(__pthread_cond_timedwait, pthread_cond_timedwait);
  52
  53 __weak_reference(_pthread_cond_init, pthread_cond_init);
  54 __weak_reference(_pthread_cond_destroy, pthread_cond_destroy);
  55 __weak_reference(_pthread_cond_signal, pthread_cond_signal);
  56 __weak_reference(_pthread_cond_broadcast, pthread_cond_broadcast);
  57
  58 static int
  59 cond_init(pthread_cond_t *cond, const pthread_condattr_t *cond_attr)
  60 {
  61         pthread_cond_t  pcond;
  62         int             rval = 0;
  63
  64         if ((pcond = (pthread_cond_t)
  65             malloc(sizeof(struct pthread_cond))) == NULL) {
  66                 rval = ENOMEM;
  67         } else {
  68                 /*
  69                  * Initialise the condition variable structure:
  70                  */
  71                 _thr_umtx_init(&pcond->c_lock);
  72                 pcond->c_seqno = 0;
  73                 pcond->c_waiters = 0;
  74                 pcond->c_wakeups = 0;
  75                 if (cond_attr == NULL || *cond_attr == NULL) {
  76                         pcond->c_pshared = 0;
  77                         pcond->c_clockid = CLOCK_REALTIME;
  78                 } else {
  79                         pcond->c_pshared = (*cond_attr)->c_pshared;
  80                         pcond->c_clockid = (*cond_attr)->c_clockid;
  81                 }
  82                 *cond = pcond;
  83         }
  84         /* Return the completion status: */
  85         return (rval);
  86 }
  87
  88 static int
  89 init_static(struct pthread *thread, pthread_cond_t *cond)
  90 {
  91         int ret;
  92
  93         THR_LOCK_ACQUIRE(thread, &_cond_static_lock);
  94
  95         if (*cond == NULL)
  96                 ret = cond_init(cond, NULL);
  97         else
  98                 ret = 0;
  99
 100         THR_LOCK_RELEASE(thread, &_cond_static_lock);
 101
 102         return (ret);
 103 }
 104
 105 int
 106 _pthread_cond_init(pthread_cond_t *cond, const pthread_condattr_t *cond_attr)
 107 {
 108         *cond = NULL;
 109         return cond_init(cond, cond_attr);
 110 }
 111
 112 int
 113 _pthread_cond_destroy(pthread_cond_t *cond)
 114 {
 115         struct pthread_cond     *cv;
 116         struct pthread          *curthread = _get_curthread();
 117         int                     rval = 0;
 118
 119         if (*cond == NULL)
 120                 rval = EINVAL;
 121         else {
 122                 /* Lock the condition variable structure: */
 123                 THR_LOCK_ACQUIRE(curthread, &(*cond)->c_lock);
 124                 if ((*cond)->c_waiters + (*cond)->c_wakeups != 0) {
 125                         THR_LOCK_RELEASE(curthread, &(*cond)->c_lock);
 126                         return (EBUSY);
 127                 }
 128
 129                 /*
 130                  * NULL the caller's pointer now that the condition
 131                  * variable has been destroyed:
 132                  */
 133                 cv = *cond;
 134                 *cond = NULL;
 135
 136                 /* Unlock the condition variable structure: */
 137                 THR_LOCK_RELEASE(curthread, &cv->c_lock);
 138
 139                 /* Free the cond lock structure: */
 140
 141                 /*
 142                  * Free the memory allocated for the condition
 143                  * variable structure:
 144                  */
 145                 free(cv);
 146
 147         }
 148         /* Return the completion status: */
 149         return (rval);
 150 }
 151
 152 struct cond_cancel_info
 153 {
 154         pthread_mutex_t *mutex;
 155         pthread_cond_t  *cond;
 156         long            seqno;
 157 };
 158
 159 static void
 160 cond_cancel_handler(void *arg)
 161 {
 162         struct pthread *curthread = _get_curthread();
 163         struct cond_cancel_info *cci = (struct cond_cancel_info *)arg;
 164         pthread_cond_t cv;
 165
 166         cv = *(cci->cond);
 167         THR_LOCK_ACQUIRE(curthread, &cv->c_lock);
 168         if (cv->c_seqno != cci->seqno && cv->c_wakeups != 0) {
 169                 if (cv->c_waiters > 0) {
 170                         cv->c_seqno++;
 171                         _thr_umtx_wake(&cv->c_seqno, 1);
 172                 } else
 173                         cv->c_wakeups--;
 174         } else {
 175                 cv->c_waiters--;
 176         }
 177         THR_LOCK_RELEASE(curthread, &cv->c_lock);
 178
 179         _mutex_cv_lock(cci->mutex);
 180 }
 181
 182 static int
 183 cond_wait_common(pthread_cond_t *cond, pthread_mutex_t *mutex,
 184         const struct timespec *abstime, int cancel)
 185 {
 186         struct pthread  *curthread = _get_curthread();
 187         struct timespec ts, ts2, *tsp;
 188         struct cond_cancel_info cci;
 189         pthread_cond_t  cv;
 190         long            seq, oldseq;
 191         int             oldcancel;
 192         int             ret = 0;
 193
 194         /*
 195          * If the condition variable is statically initialized,
 196          * perform the dynamic initialization:
 197          */
 198         if (__predict_false(*cond == NULL &&
 199             (ret = init_static(curthread, cond)) != 0))
 200                 return (ret);
 201
 202         cv = *cond;
 203         THR_LOCK_ACQUIRE(curthread, &cv->c_lock);
 204         ret = _mutex_cv_unlock(mutex);
 205         if (ret) {
 206                 THR_LOCK_RELEASE(curthread, &cv->c_lock);
 207                 return (ret);
 208         }
 209         oldseq = seq = cv->c_seqno;
 210         cci.mutex = mutex;
 211         cci.cond  = cond;
 212         cci.seqno = oldseq;
 213
 214         cv->c_waiters++;
 215         do {
 216                 THR_LOCK_RELEASE(curthread, &cv->c_lock);
 217
 218                 if (abstime != NULL) {
 219                         clock_gettime(cv->c_clockid, &ts);
 220                         TIMESPEC_SUB(&ts2, abstime, &ts);
 221                         tsp = &ts2;
 222                 } else
 223                         tsp = NULL;
 224
 225                 if (cancel) {
 226                         THR_CLEANUP_PUSH(curthread, cond_cancel_handler, &cci);
 227                         oldcancel = _thr_cancel_enter(curthread);
 228                         ret = _thr_umtx_wait(&cv->c_seqno, seq, tsp);
 229                         _thr_cancel_leave(curthread, oldcancel);
 230                         THR_CLEANUP_POP(curthread, 0);
 231                 } else {
 232                         ret = _thr_umtx_wait(&cv->c_seqno, seq, tsp);
 233                 }
 234
 235                 THR_LOCK_ACQUIRE(curthread, &cv->c_lock);
 236                 seq = cv->c_seqno;
 237                 if (abstime != NULL && ret == ETIMEDOUT)
 238                         break;
 239
 240                 /*
 241                  * loop if we have never been told to wake up
 242                  * or we lost a race.
 243                  */
 244         } while (seq == oldseq || cv->c_wakeups == 0);
 245
 246         if (seq != oldseq && cv->c_wakeups != 0) {
 247                 cv->c_wakeups--;
 248                 ret = 0;
 249         } else {
 250                 cv->c_waiters--;
 251         }
 252         THR_LOCK_RELEASE(curthread, &cv->c_lock);
 253         _mutex_cv_lock(mutex);
 254         return (ret);
 255 }
 256
 257 int
 258 _pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
 259 {
 260         return cond_wait_common(cond, mutex, NULL, 0);
 261 }
 262
 263 __strong_reference(_pthread_cond_wait, _thr_cond_wait);
 264
 265 int
 266 __pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
 267 {
 268         int ret;
 269
 270         ret = cond_wait_common(cond, mutex, NULL, 1);
 271         return (ret);
 272 }
 273
 274 int
 275 _pthread_cond_timedwait(pthread_cond_t * cond, pthread_mutex_t * mutex,
 276                        const struct timespec * abstime)
 277 {
 278         if (abstime == NULL || abstime->tv_sec < 0 || abstime->tv_nsec < 0 ||
 279             abstime->tv_nsec >= 1000000000)
 280                 return (EINVAL);
 281
 282         return cond_wait_common(cond, mutex, abstime, 0);
 283 }
 284
 285 __strong_reference(_pthread_cond_timedwait, _thr_cond_timedwait);
 286
 287 int
 288 __pthread_cond_timedwait(pthread_cond_t *cond, pthread_mutex_t *mutex,
 289                        const struct timespec *abstime)
 290 {
 291         if (abstime == NULL || abstime->tv_sec < 0 || abstime->tv_nsec < 0 ||
 292             abstime->tv_nsec >= 1000000000)
 293                 return (EINVAL);
 294
 295         return cond_wait_common(cond, mutex, abstime, 1);
 296 }
 297
 298 static int
 299 cond_signal_common(pthread_cond_t *cond, int broadcast)
 300 {
 301         struct pthread  *curthread = _get_curthread();
 302         pthread_cond_t  cv;
 303         int             ret = 0;
 304
 305         /*
 306          * If the condition variable is statically initialized, perform dynamic
 307          * initialization.
 308          */
 309         if (__predict_false(*cond == NULL &&
 310             (ret = init_static(curthread, cond)) != 0))
 311                 return (ret);
 312
 313         cv = *cond;
 314         /* Lock the condition variable structure. */
 315         THR_LOCK_ACQUIRE(curthread, &cv->c_lock);
 316         if (cv->c_waiters) {
 317                 if (!broadcast) {
 318                         cv->c_wakeups++;
 319                         cv->c_waiters--;
 320                         cv->c_seqno++;
 321                         _thr_umtx_wake(&cv->c_seqno, 1);
 322                 } else {
 323                         cv->c_wakeups += cv->c_waiters;
 324                         cv->c_waiters = 0;
 325                         cv->c_seqno++;
 326                         _thr_umtx_wake(&cv->c_seqno, INT_MAX);
 327                 }
 328         }
 329         THR_LOCK_RELEASE(curthread, &cv->c_lock);
 330         return (ret);
 331 }
 332
 333 int
 334 _pthread_cond_signal(pthread_cond_t * cond)
 335 {
 336         return cond_signal_common(cond, 0);
 337 }
 338
 339 __strong_reference(_pthread_cond_signal, _thr_cond_signal);
 340
 341 int
 342 _pthread_cond_broadcast(pthread_cond_t * cond)
 343 {
 344         return cond_signal_common(cond, 1);
 345 }
 346
 347 __strong_reference(_pthread_cond_broadcast, _thr_cond_broadcast);